Method of making alloys



, Patented Nov 10, l9255 RICHABD -WALTER, 0E

nussnrinoar, GERMANY.

Imarnon or MAKING ALLOYS;

No Drawing.

- specification.

My invention has reference to improve- "ments in the manufacture of acid-proof alloys, and relates more specifically to a new and improved 'method 'of making alloys of heavy metals, such as the metals of the iron and chromium groups, with silicon. The iron group comprises iron, manganese, nickel, and cobalt. And to the chromium group belong chromium, tungsten, molybdenum, and uranium. t

As well known in the art the acid-proofness of alloys of metals of the iron and k v plete llquefaction and the formatlon of an" chromium groups with silicon is due to the silicides of the components of said alloys, such as for instance the silicides of the iron, of the chromium, of the nickel, et cetera, and thus we find for instance in the most used alloys of silicon with irpn the silicides Fe Si, FeSi and FeSi As can readily be verified by chemical and'metallographic tests there .will always be found present simul-' taneously several of these combinations in the acid-resisting iron-silicon alloys known so far. Themanufacture of the above mentioned acid-proof alloys presents, as is'well known, numerous difiiculties as regards the art of castingand molding. The castings show a relatively 'low mechanical strength and are apt to crack during cooling in. the "molds, owing to their pronounced contraction and internal stress of material.

I have found that this disadvantageous phenomenon is due principally to the coexistence or association of two' or more of the silicides in the above named alloys, as the outsi e heat to a temperature somewhat be Application filed June 29, 1920. Serial No. 392,895.

low the fusing points of the components at which sudden exothermic reaction sets in, which will then almost instantaneously melt down the, charge. The temperature at which this reaction takes place lies between 1200 and 1300 C. The reaction starts with an abruptcrise in the temperature curve and will then quickly, almost instantaneously,

flash through the entire charge. In practi cal operation the entire charge of a large furnace, after the reaction temperature has been reached and reaction has set in at. a

.single'spot, will spontaneously melt down wlthin a few seconds. The reaction may also be started by prodding or striking the solid charge with an iron rod whereby local pressure between the more or less loosely contacting coniponentsis exerted.- The result of this violentheat reaction is a com-,

1 alloy containing only one single homogene:

ous silicide.

My'investigations have shown that the described process can be used equally well in the case of other metals of the iron group, and not'o'nly iron, such as for in.

stance manganese, nickel, cobalt and others,

with a 20% silicon content the iron and the ferrosilicon strictly in stoichiometrical duction of 1000 kilograms of an iron alloy weight proportion corresponding to a silicide of the ormula Fe Si. This proportion is- 780 kilograms iron and 220 kilograms high-percent ferrosilicbn (90%). Then I treatthis mixture in the above described manner by bringing it by outside heat to the point of reaction (1200-1300 C). In this temperature interval the exothermic reaction sets in which ends in the produption' if gr wlloy-corresponding. to the formula e 1. 1

Whatl claim is:-- w 1.v The hereinbefore described process of making) alloys of silicon and heavyumetals, which consists in mixing the components in .proper proportion for the formation of a single homogeneous silicide, in then heating the mixture to atemperature at which exotherrnic reaction is initiated, and in then using this reaction to melt down the charge.

2. The hereinbefore described process of making alloys. of silicon and iron, which consists in mixing the components in proper proportion for the formation of a single homogeneous silicide, in then heating the mixture to a temperature at which exothermic reaction is initiated, and in then using this reaction heat to melt down the charge.

3. The hereinbefore described process of making alloys of metals of the iron and chromium groups and silicon,- which consists in mixing the components in proper proportion for the. formation of a single homogeneous silicide, in then heating the mixture to a temperature between the limits of 1200 to 1300 C., and in then using tion substantially corresponding to the stoichiometrical proportion of the constituents of a single homogeneous silicide, in then heating the mixture by outside heat to a temperature somewhat below the fusing point of the components at which exothermic reaction sets in, and. in then using this reaction heat to complete the process.

In testimony whereof I aflix my signature.

RICHARD WALTER. 

